Self-straightening suction wand



Sept. 13, 1966 e. 1.. NEELY SELF-STRAIGHTENING SUCTION WAND Filed July 1, 1965 w u s E m E a mm M m N L f R .6 m w A F G E E o r I 1 v G T ummml F N R T l. G I a F n Y B x 3 G F 2 A 9 7 7 1 I U 3 m F United States Patent 3,272,535 SELF-STRAIGHTENING SUCTION WAND George L. Neely, Berkeley, tCalif., assignor to tlhevron Research Company, a corporation of Delaware Filed July 1, 1963, Ser. No. 292,012 1 Claim. (Cl. 285-414) This invention relates to suction tubes, or wands, for removing hot lubricating oil from automobile engines, transmissions, gear cases or the like. More particularly, it relates to an improved suction wand able to enter the engine through the normal convolutions and small diameter passage provided by a dip stick tube to remove lubricating oil from the engine.

It is a particular object of this invention to provide a flexible and rugged gas-tight tube having a maximum diameter that will permit it to pass through many forms of dip stick tubes found in modern automobiles so that the tube may be easily inserted to contact the bottom of the crankcase which forms the sump for engine lubricating oil. In carrying out this object, the suction Wand is constructed of a tightly coiled spring member wherein the turns are in substantial preloaded contact with each other throughout their length, and the external surface of the spring member is slidably inserted in a thin, pliant plastic material whose internal diameter is not greater than about the external diameter of the coil spring. By this arrangement, when the coil spring is placed under bending stress, as during insertion of the wand into the engine through the dip stick tube, the coil spring member is free to bend and slide readily within the plastic covering. It will thereby conform to the convolutions through the engine dip stick tube as well as accessories external to the engine and passageways within the engine. In a preferred form of apparatus, one end of the coil spring member extends slightly beyond the end of the plastic material; the length of exposure of this end becomes greater as the spring bends more. This exposed end may have the coils 'bonded together to insure a continuous tube through which spent oil may be sucked up without losing vacuum through the turns of the coil when the fluid level is lower than the bottom end of the plastic slip cover. Additionally, such extension of the coil spring member provides an electrical circuit by which contact of the lower end of the wand may be indicated when an operator is inserting it into an engine crankcase.

In my application Serial No. 151,494, filed November 10, 1961, now Patent Number 3,095,062 for an oil change system, there is disclosed apparatus for removing spent lubricating oil from an automobile engine, or the like, through a dip stick tube. In this application, there is disclosed a wand that comprises a plastic tube and an elongated, conducting metal rod that is loose and therefore free to deform within the plastic tube. A primary purpose of this member is to form an electrical conductor to indicate when the lower end of the suction wand is touching bottom in the engine pan. In removing heated engine oil, as when the engine is hot, it has been found that the plastic tube may become deformed and take substantially a permanent set in this shape when it cools. Additionally, the metal rod is sometimes bent beyond its yield point when the radius of bend in the dip stick tube is too small, say less than 2 inches. Further, under certain high vacuum conditions the plastic tube is subject to collapse unless the walls are relatively thick. Within the limits imposed by the inside diameter of the dip stick, it is, of course, desirable to obtain maximum fiow rates in pulling oil from the engine crankcase in this manner. Accordingly, the suction wand must be as rigid and nearly a self straightening structure as possible. And, at the same time, adding to the overall diameter permitting an adequate minimum bending radius and a maximum inside diameter of the coiled metal spring that forms the flow passage through the Wand. A suction wand, constructed of preloaded turns to form a helical coil member and covered with a thin slidable plastic sleeve, as will be explained in the detailed description of preferred embodiments of my invention, satisfies these demanding conditions. Other objects and advantages of this invention will become apparent from the following detailed description.

In the drawings,

FIG. 1 is a schematic representation of an oil change system using a suction wand.

FIG. 2 illustrates a preferred embodiment by an improved suction Wand according to my invention.

FIG. 3 is an alternate arrangement of the coil spring member using square wire.

FIG. 4 is a further alternate structure of the coil using wire of truncated-triangular, or keystone, cross section.

Referring now to the drawings and in particular FIG. 1, suction wand 10, constructed in accordance with this invention, is used to withdraw used lubricating oil from the bottom of engine 11 through dip stick tube 12 of automobile 13. Suction is applied to wand 10 by pump unit 14. As indicated, dip stick tube 12 is normally curved, and sometimes even assumes the form of an S- shaped curve to avoid air-conditioners, air filters and the like. It is, of course, intended to guide a bayonet-form of dip stick (not shown) as used in most automobiles to indicate the level of lubricating oil in engine 11. Tube 12 will normally have .an inside diameter of not over about /a inch; most frequently it may be as small as 7 inch. Furthermore, when engine oil is to be removed from the car after it has been operating long enough for the engine to be at operating temperature, the oil will be hot. This is generally in the range of l60-250 F. Since the purpose of the oil change system, such as that illustrated by pump unit 14, is to permit a service station operator to remove the oil while gasoline is being pumped into the fuel tank, it is important that the flow rate through wand 10 be as fast as possible.

In accordance with the present invention, wand 10, as illustrated in FIG. 2, comprises basically a tightly coiled metal spring member 17. The helical turns of the coil spring are wound so that under a condition of no bending or longitudinal tension, the individual turns contact each other under a preloaded 0r prestressed condition throughout the length of the Wand. The external diameter of coil 17 should be as large as possible to slide through plastic cover tube 19. For use in engines with dip stick tubes having an inside diameter of inch, a suitable outside diameter of coil 17 is about 0.220 inch and it is suitably wound from music wire having a diameter of about 0.032 inch; plastic sleeve 19, then, has an outside diameter of 0.250 inch and an inside diameter of 0.225 inch. The length of coil 17 will vary depending upon the type of automobiles to be serviced, but in general it will be on the order of 2 /2 to 3 /2 feet long, to permit the coil to pass readily through the convolutions around and over parts of the engine and the tortuous path through the clip stick tube 12.

Contact between the individual turns of the coil is not maintained on the outside radius when coil 17 is bent. Furthermore, each turn, when so spread apart, presents a possible snag for the entire coil assembly as it is inserted through tube 12. In most automobiles, dip stick tube 12 has relatively sharp edges, particularly on the lower end. Thus, a pliant cover, or tube, 19 formed of thin plastic material serves as a vapor-type seal between the turns opened by bends in coil 17, during evacuation of the crankcase, and at the same time prevents snagging of the coil 17 when it is inserted and withdrawn from tube 12.

Except at their upper ends, coil 17 and cover 19 are not secured together. With the dimensions given above, coil 17 is free to slip relative to tube 19 to give coil spring 17 maximum self-straightening characteristics. This is assisted by the oil film that lubricates spring 17 in sleeve 19. Cover may be suitable formed of nylon, or Teflon, or other organic polymeric plastic materials, capable of withstanding the operating temperatures at which lubricating oil is drawn from the engine.

A further advantage of this structure is that if the suction wand enters the crankcase at a shallow angle to bottom, coil spring member 17 tends to hold itself on bottom rather than curl up and rise off bottom. This feature is also due to the self-straightening character of the preloaded coils used to form my wand assembly.

In the present embodiment, the upper end of coil 17 is secured to a bayonet connector, generally identified as 23, by collar 25 and nut 27. They clamp the upper end of spring 17 between them through pigtail assembly 29, formed by wrapping the upper end of coil 17 around a mandrel of larger diameter for three or four turns, to clamp pliant tube 19 to spring 1'7, inset 31 is formed in nut 27. Inset 31 is of sufficient diameter to accept the upper end of cover 19, and then nut 33 tightens coil spring 17 and tube 19 together. This connection makes possible easy replacement of tube 19 if it is physically damaged.

In the arrangement of FIG. 2, end 21 may include bonding of the last few turns of spring member 17. This can be done by dipping end 21 in solder, or the like, so that the individual coils are sealed by solder, as indicated at 35. This precaution is taken where it is known that the lower end of the tube may be subjected to severe bending or is likely to be caught on the sharp edges of dip stick tube 12; specifically, even where the end of the coil 17 does not extend as far beyond tube 19 as it does in FIG. 2, it is desirable to so seal the last few turns because when tube 17 is bent, it elongates so that a. few of the turns within tube 19 protrude. However, it is not always necessary for the coil even to extend beyond the end of cover 19. Specifically, where the coil does not serve as an electrical conductor, or only a few turns, say 2 or 3, extend beyond cover 19, it is not necessary to bond these coils.

FIG. 3 and FIG. 4 illustrate other forms of wire that can be used to form coil 17 which acts as a stiffener member for plastic cover 19. Specifically, the wire may be square in cross-sectional area as in FIG. 3, or it may have a truncated-triangular, or keystone, shape as in FIG. 4. In all other respects, the coil is formed substantially the same way as in the arrangement of FIG. 2. A particular advantage of square wire, as in FIG. 3, is that the area contact between the walls adjacent the coils is increased so that contact between each turn is more readily achieved and more self-straightening effect of coil 17 is achieved.

The arrangement of FIG. 4 is for the same purpose of obtaining better self straightening of coil member 17B after bending. In this arrangement there is somewhat less friction between the individual coils than in FIG. 3 so that greater flexibility is obtained when the wand is laterally bent on insertion into an engine.

From the following description it can be seen that a suction wand formed of a plastic tube of relatively thin cross section, which would normally be incapable of supporting itself against collapse when used as a vacuum tube, is stiffened by an elongated, helically wound coil member whose turns are preloaded relative to each other and whose external diameter slidably engages the internal diameter of the plastic tube. This arrangement provides a maximum internal diameter suction wand for removing the spent lubricating oil in an automobile engine through the dip stick tube; at the same time, the wand will be self straightening and will withstand sharp bending without taking a permanent set (kinking).

Various changes in the structure shown and described will occur to those skilled in the art. All such changes that fall within the scope of the appended claim are intended to be included therein.

I claim:

A suction wand for removing lubricating oil from the crankcase of an internal combustion engine through the dip stick tube, which comprises (a) an elongated organic, polymeric plastic tube having a wall thickness thin enough to permit collapse thereof by air pressure upon the application of suction therethrough,

(b) said plastic tube having a uniform outer diameter adapted to pass downwardly through a dip stick tube into an engine crankcase,

(c) an elongated coil spring coextensive in length with said tube and having a uniform outer diameter substantially identical to the inner diameter of said plastic tube to permit frictional engagement between said tube and said spring throughout their lengths,

(d) said coil spring comprising a helical winding of spring wire sound sufiiciently tight so that the individual turns are in preloaded contact with each other throughout the length of said coil spring, said preloaded contact being sufiicient to provide selfalignment of said member and closing contact between said winding when not subjected to bending stresses, said coil spring and said plastic tube being secured together only at the end remote from the end adapted to enter the engine dip stick tube so that said coil spring will conform said plastic tube to the convolutions in said dip stick tube while still maintaining frictional engagement therebetween and so that upon withdrawal of said plastic tube and coil spring, said coil spring will straighten said plastic tube to its substantially undeflected form by slight relief of the preloaded contact between said individual turns of said spring and by slippage between the inner diameter of said tube and said coil spring, and

(e) means for connecting said remote end of said tube and said coil spring to vacuum applying means for removing oil from an engine crankcase.

References Cited by the Examiner UNITED STATES PATENTS 1,481,341 1/1924 Bersted 138--134 X 2,020,350 11/1935 Bertschinger 1841.5 2,477,450 7/1949 Gray 184-1.5 3,095,062 6/1963 Neely 148-l.5

FOREIGN PATENTS 376,962 7/1932 Great Britain.

CARL W. TOMLIN, Primary Examiner.

S. R. MILLER, R. GIANGIORGI, Assistant Examiners. 

